The present invention is directed to a stage assembly for moving a device. More specifically, the present invention is directed to a stage assembly including a reaction mass assembly for an exposure apparatus.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that retains a reticle, a lens assembly and a wafer stage assembly that retains a semiconductor wafer. The reticle stage assembly and the wafer stage assembly are supported above a ground with an apparatus frame.
Typically, the wafer stage assembly includes a wafer stage base, a wafer stage that retains the wafer, and a wafer stage mover assembly that precisely positions the wafer stage and the wafer. Somewhat similarly, the reticle stage assembly includes a reticle stage base, a reticle stage that retains the reticle, and a reticle stage mover assembly that precisely positions the reticle stage and the reticle. The size of the images transferred onto the wafer from the reticle is extremely small. Accordingly, the precise relative positioning of the wafer and the reticle is critical to the manufacturing of high density, semiconductor wafers.
Unfortunately, the wafer stage mover assembly generates reaction forces that can vibrate the wafer stage bass and the apparatus frame. The vibration influences the position of the wafer stage base, the wafer stage, and the wafer. As a result thereof, the vibration can cause an alignment error between the reticle and the wafer. This reduces the accuracy of positioning of the wafer relative to the reticle and degrades the accuracy of the exposure apparatus.
In light of the above, one object of the present invention is to provide a stage assembly that precisely positions a device. Another object is to provide a stage assembly that minimizes the influence of the reaction forces of the stage mover assembly upon the position of the stage, the stage base, and the apparatus frame. Still another object is to provide a stage assembly having an improved reaction mass assembly. Yet another object is to provide an exposure apparatus capable of manufacturing precision devices such as high density, semiconductor wafers.
The present invention is directed to a stage assembly for moving a device relative to a stage base that satisfies these needs. The stage assembly includes a stage, a stage mover assembly, and a reaction mass assembly. The stage retains the device. The stage mover assembly is connected to the stage and moves the stage relative to the stage base with at least two degrees of freedom. The reaction mass assembly is coupled to the stage mover assembly.
A number of embodiments of the reaction mass assembly are provided herein. Uniquely, in each embodiment, the reaction mass assembly reduces the reaction forces created by the stage mover assembly in at least two degrees of freedom that are transferred to the stage base. As a result thereof, the stage assembly can more accurately position the device. Further, the stage assembly can be used in an exposure apparatus to manufacture high density, high quality semiconductor wafers.
As provided herein, the stage mover assembly can include one or more X stage movers and one or more Y stage movers that are coupled to the reaction mass assembly. The X stage movers move the stage along an X axis, and about a Z axis, while the Y stage movers move the stage along a Y axis. The stage mover assembly generates reaction forces in at least two degrees of freedom.
In the embodiments provided herein, the reaction mass assembly includes an X reaction component and a Y reaction component. The X reaction component moves relative to the stage base with at least to degrees of freedom and more preferably, three degrees of freedom. The Y reaction component moves relative to the stage base with at least one degree of freedom and more preferably three degrees of freedom.
Further, in the embodiments provided herein, the X reaction component is coupled to the Y reaction component and moves relative to the Y reaction component along the X axis. Additionally, the X reaction component and the Y reaction component move concurrently along the Y axis relative to the stage base. In some of the embodiments, the X reaction component and the Y reaction component also move concurrently along the X axis and about a Z axis relative to the stage base.
Preferably, the stage assembly also includes a reaction mover assembly that adjusts and corrects the position of the reaction mass assembly relative to the stage base. As provided herein, the reaction mover assembly can adjust the position of the reaction mass assembly relative to the stage base in one degree of freedom and more preferably in three degrees of freedom. For example, the reaction mover assembly can (i) move the X reaction component relative to Y reaction component along the X axis, (ii) move the X reaction component and the Y reaction component concurrently relative to the stage base along the Y axis, (iii) move the X reaction component and the Y reaction component concurrently relative to the stage base along the X axis, and/or (iv) move the X reaction component and the Y reaction component concurrently relative to the stage base about a Z axis. Further, as provided herein, the reaction mover assembly can be disposed independently from the stage movers.
The present invention is also directed to a method for making a stage assembly, a method for making an exposure apparatus, a method for making a device and a method for manufacturing a wafer.